Platelet extracellular vesicles are superior to cardiac troponin to diagnose acute coronary syndrome with short symptom duration: LEMONADE trial

Background

Acute coronary syndrome (ACS), which comprises acute myocardial infarction (AMI) and unstable angina pectoris (UAP), is one of the main causes of mortality worldwide. Cardiac troponin is the gold standard to diagnose AMI. Troponin has two main disadvantages: it is negative in patients with UAP but positive in other diseases. During ACS, activated platelets release extracellular vesicles (EVs), which promote coagulation and associate with fibrin, and contribute to thrombus formation. We hypothesized that the concentration and composition of circulating platelet EVs (1) change in blood of patients with ACS compared to patients with other causes of chest pain, and (2) thereby allow earlier diagnosis of ACS than cardiac troponin.

Purpose

We aimed to determine the diagnostic value of circulating platelet EVs as novel early biomarkers of developing ACS.

Methods

We conducted a prospective, multicentre trial enrolling 105 patients who presented to the emergency department with suspected ACS. Blood was collected at admission to measure the concentration of EVs and cardiac troponin. Flow cytometry (Apogee A60-Micro) was used to determine plasma concentrations of platelet EVs exposing P-selectin (CD61+/CD62p+) and fibrin (CD61+/fibrin+).

Results

Plasma concentrations of platelet EVs exposing fibrin was lower in patients with ACS, compared to patients with other causes of chest pain (p=0.023) and lower in patients with an occlusive thrombus compared to non-occlusive plaque (p=0.015). Fibrin exposing-EVs were independent predictors of ACS (OR 8.2, CI 1.3–16.4) in multivariate analysis, allowing to diagnose ACS with 75% sensitivity and 72% specificity. Among patients with pain onset less than 2 hours before presentation, fibrin-exposing EVs had substantially better diagnostic performance than troponin (area under the ROC curve 0.90 vs. 0.74, respectively). Regarding other causes of chest pain, fibrin-exposing EVs were the lowest in patients with ACS, higher in patients with other cardiological causes of chest pain, and the highest in patients with non-cardiological causes of chest pain (p=0.036).

Conclusions

Circulating fibrin-exposing EVs are early biomarkers of developing ACS, superior to cardiac troponin in patients with pain onset less than 2 hours before presentation. Incorporation of EV measurements into the ACS diagnostic algorithm might revolutionise thrombotic risk stratification in the emergency setting.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Specialised Research Fellowship, “Club 30” of the Polish Society of Cardiology

Flavonoid glucuronides with anti-leukaemic activity from Polygonum amphibium L

INTRODUCTION

The chemical and pharmaceutical studies carried out on species from Polygonum L. genus showed biological activity both of the extracts and the components isolated from them. These results were the impulse to examine Polygonum amphibium L.

OBJECTIVE

The aim of this study was the isolation of active components from methanol extract and the determination of their cytotoxic effect on human leukaemic cell lines.

METHODOLOGY

Three flavonoid components from butanol soluble fractions of methanol extract by CC and PC preparative chromatography were isolated. Their structures were established on the basis of 1H, 13C and correlation (DEPT, H-H, COSY, HMQC, HMBC) NMR, UV and FAB-MS spectroscopic techniques. The evaluation of the anti-leukaemic activities of 1 and 2 against Jurkat and HL60 cell lines was carried out in vitro using annexin V fluorescence assay.

RESULTS

Two new flavonoid glucuronides, quercetin-3-O-beta-glucuronide (1) and quercetin-3-O-alpha-rhamnosyl-(1 --> 2)-beta-glucuronide (2), and kaempferol-3-O-alpha-rhamnosyl-(1 --> 2)-beta-glucuronide (3), were isolated from Polygonum amphibium L. It was demonstrated that the glucuronides of quercetin are able to induce apoptosis in the tested human leukaemic cells. These compounds penetrate through cytoplasm to the cellular nucleus of the cultured cells, and give intensive apoptotic responses in the stimulated leukaemic cells. The number of apoptotic cells increased with the concentration (1 nm to 10 microm) of 1 or 2 and periods of exposure (1-3 days).

CONCLUSION

Compounds 1 and 2 may be considered good candidates for leukaemia chemotherapeutic agents.

The flavonoids, quercetin and isorhamnetin 3-O-acylglucosides diminish neutrophil oxidative metabolism and lipid peroxidation

Two natural flavonoids, quercetin and isorhamnetin 3-O-acylglucosides, were examined for their inhibitory influence on the in vitro production and release of reactive oxygen species in polymorphonuclear neutrophils (PMNs). The generation of superoxide radical, hydrogen peroxide and hypochlorous acid were measured by, respectively, cytochrome c reduction, dichlorofluorescin oxidation and taurine chlorination. Membrane lipid oxidation was studied by the thiobarbituric acid method in mouse spleen microsomes. The addition of flavonoids at the concentration range 1-100 microM inhibited PMNs oxidative metabolism and lipid peroxidation in a dose-dependent manner. The results suggest that these flavonoids suppress the oxidative burst of PMNs and protect membranes against lipid peroxidation.

Phenolic compounds in two Solidago L. species from in vitro culture

The regenerated S. virgaurea and S. graminifolia, obtained previously by micropropagation from shoot tips and the callus tissue of S. virgaurea, were analysed for phenolic compounds. Preliminary used 2D-TLC methods (fingerprinting) showed the presence of phenolic glucoside--leiocarposide (S. virgaurea only), C-glycosyflavones--schaftoside and isoschaftoside (S. graminifolia), flavonoids and caffeoylquinic acids, similar to the ones reported earlier for naturally growing plants with the exception of the callus tissue. The latter contained predominantly caffeoylquinic acids, which were isolated and identified by NMR as 5-O-caffeoylquinic and 3,5-di-O-caffeoylquinic acids. The content of leiocarposide (HPLC) and flavonoids (colorimetry) in S. virgaurea was determined.

The flavonoids, quercetin and isorhamnetin 3-O-acylglucosides diminish neutrophil oxidative metabolism and lipid peroxidation

Two natural flavonoids, quercetin and isorhamnetin 3-O-acylglucosides, were examined for their inhibitory influence on the in vitro production and release of reactive oxygen species in polymorphonuclear neutrophils (PMNs). The generation of superoxide radical, hydrogen peroxide and hypochlorous acid were measured by, respectively, cytochrome c reduction, dichlorofluorescin oxidation and taurine chlorination. Membrane lipid oxidation was studied by the thiobarbituric acid method in mouse spleen microsomes. The addition of flavonoids at the concentration range 1-100 microM inhibited PMNs oxidative metabolism and lipid peroxidation in a dose-dependent manner. The results suggest that these flavonoids suppress the oxidative burst of PMNs and protect membranes against lipid peroxidation.

Naphthoquinone glucosides of Drosera gigantea from in vitro cultures

From the shoots of Drosera gigantea propagated under in vitro culture, the rare naphthoquinone glucosides droserone (3,5-dihydroxy-2-methyl-1,4-naphthoquinone) and hydroxydroserone (3,5,8-trihydroxy-2-methyl-1,4-napthoquinone) 5-O-beta-glucosides, together with the free naphthoquinones droserone, hydroxydroserone and plumbagin were isolated. The structures of the glucosides and hydroxydroserone were studied by 2D NMR techniques. The glucosides appear to be responsible for the brown-red (maroon) colour of this plant. Of the other naphthoquinones typical for the family Droseraceae only hydroplumbagin glucoside could be detected, whereas the presence of 7-methyljuglone and rossoliside (= 7-methylhydrojuglone glucoside) was excluded.

Microvascular protective activity of flavonoid glucuronides fraction from Tulipa gesneriana

A mixture of flavonoid glucuronides, consisting of 7-O-glucuronides of kaempferol and quercetin 3-O-rutinosides, 3-O-gentiobiosides and 3-O-glucosides, was isolated from the perianths of Tulipa gesneriana L. var. 'Paradae'. It showed protective activity against the increased (both chloroform and histamine) skin vascular permeability in rabbits. The protective effect, measured as the reduction in leakage of Evans blue, was 59.8% after peritoneal treatment at a dose of 25 mg/kg, while that of troxerutin was 45.5%.

Phenylpropanoid esters from Lamium album flowers

Two phenylpropanoid glycosides, a new one, lamalboside (2R-galactosylacteoside) and the known acteoside, the flavonol p-coumaroylglucoside, tiliroside, 5-caffeoylquinic acid (chlorogenic acid), along with rutoside and quercetin and kaempferol 3-O-glucosides were isolated from the flowers of Lamium album. Esters of glycosides were obtained as mixtures of trans/cis isomers. The presence of flavonoid p-coumaroylglucosides links Lamium to other members of the subfamily Lamioideae.

Studies on antioxidative activity of some C-glycosylflavones

Ten flavonoid C-glycosyl derivatives: orientin (1), isoorientin (2), vitexin (3), isovitexin (4), isovitexin 7,2"-di-O-glucoside (5), isovitexin 7-O-galactoside-2"-O-glucoside (6), two different 6,8-di-C-hexosylapigenins (7, 8), and two different 6-C-hexosyl-8-C-pentosylapigenins (9, 10) have been either produced from flavonoid fractions from Adonis vernalis L. (1, 2) and Crataegus species (3, 4), or isolated from Stellaria media (L.) Vill. (5-10) to study their antioxidative properties. These were found only for two compounds: orientin (1) and isoorientin (2).

[Nitrogenous triterpene derivatives. 10. Hemisuccinates of some oleanolic acid derivatives and their antiulcer effect]

The synthesis of hemisuccinates of some derivatives of oleanolic acid is reported, their inhibitory response to experimentally induced gastric ulcers in rats is examined. The hemisuccinates 13a (sodium salt of 13), 14 and 17 are more effective inhibitors than carbenoxolon-sodium.

[Nitrogenous triterpene derivatives. 9. 3-Acetyloleanol acid-28-amides and their antiulcer effect]

The authors report on the synthesis of 3-acetyloleanol acid-28-amids 10, 12-16, 19, 20, 22 and 24. The amids 16 (30%) and 24 (37%) were of most favourable inhibiting effect on the formation of gastric ulcera following pylorus ligature. The ulcer formation caused by p. o. administration of indometacin (Metindol) was in the main reduced by the amids 15 (60%), 16 (34%), and 24 (46%). With both the methods the effect of carbenoxolon sodium amounts to 40 or 50%. In ulcera induced by indometacin, the 11- and 3-oxooleanol acid derivates 12 and 18 revealed stimulating characteristics.